Explictly try to find a working compiler, needed because some
binary installers for Python have a reference to a compiler that
doesn't work on OSX 10.8 (or rather 'with Xcode 4').
See also <http://bugs.python.org/issue13590>
Fixes #30

Sync pyobjc_setup.py: all framework wrappers once again have the same copy
Also:
- license= argument for distutils.core.setup() added
- include the version constraints in the platforms= argument
when known.